• 생명과학회지
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• 제26권7호
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• pp.826-834
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• 2016

본 연구는 Hsp90 inhibitor 및 SIRT1 inhibitor의 병용처리가 항암제 다제내성(MDR) 인간 암세포의 증식 억제에 효과적임을 밝혔다. SIRT1 활성 억제가 Hsp90 inhibitor인 17-AAG의 세포 독성의 효과를 증강시켰으며, 이로 인해 Hsp90 inhibitors에 대한 내성을 극복시킬 수 있음을 인간 자궁암세포인 HeyA8의 MDR 변이주인 HeyA8- MDR 세포에서 확인하였다. SIRT1 inhibitor는 Hsp90 inhibitor에 의한 Hsp90 샤페론 기능 억제를 증강시키며, ubiquitin ligase CHIP의 발현 증강을 유발하여, Hsp90 client protein 인 mutant p53 (mut p53)의 분해를 촉진시킨다. Mut p53 의 발현 감소는 암세포의 Hsp90 inhibitor 내성 획득의 가장 중요한 원인으로 지적되는 heat shock factor 1 (HSF1)/heat shock proteins (Hsps)의 발현 억제와 관련됨을 알 수 있었으며, 이는 항암제 다제내성 세포에서 SIRT1 inhibitor에 의하여 Hsp90 inhibitor에 대한 감수성이 증강되는 분자적 기전임을 밝혔다. 그러므로, SIRT1 억제에 의한 mut p53/HSF1 발현 감소가 MDR 암세포의 Hsp90 inhibitors 내성 극복에 매우 유효함을 시사하는 결과를 얻었다.

• International Journal of Molecular Medicine
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• 제44권3호
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• pp.1161-1171
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• 2019

The present study investigated whether glucagon like peptide-1 (GLP-1) improves glucose uptake through glucose transporter type 4 (GLUT4), mediated by the activation of sirtuin 1 (SIRT1), in skeletal muscle cells with palmitate induced-insulin resistance. The levels of glucose uptake, GLUT4, protein kinase A (PKA), and cyclic adenosine monophosphate (cAMP) were determined in human skeletal muscle myotubes (HSMMs) exposed to palmitate and GLP-1. Then, to determine whether PKA/cAMP were downstream signals of GLP-1, a PKA inhibitor was used. To determine whether SIRT-1 contributes to GLP-1 action in HSMMs with palmitate-induced insulin resistance, the levels of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) deacetylation and SIRT-1 activity were assessed using a SIRT1 inhibitor and small interfering RNA (siRNA). The phosphorylation levels of protein kinase B (Akt) and insulin receptor substrate 1 (IRS-1) as insulin signaling pathways, were assessed in GLP-1-treated HSMMs exposed to palmitate. The influence of SIRT1 on the GLP-1-induced activation of insulin signaling pathway was determined using a SIRT1 inhibitor. GLP-1 restored the palmitate-induced reductions in the levels of glucose uptake, GLUT4 mRNA, GLUT4 promoter activity, and GLUT4 protein in HSMMs. PKA and cAMP, as GLP-1 downstream signals, played a role in this process. GLP-1 increased the deacetylation levels of PGC1α, and stimulated SIRT1 in HSMMs. Moreover, the SIRT1 inhibitor and siRNA of SIRT1 suppressed the effect of GLP-1 on GLUT4 expression in HSMMs exposed to palmitate. The SIRT1 inhibitor also prevented the GLP-1-induced phosphorylation of IRS-1 and Akt in palmitate-treated HSMMs. The present findings suggest that in palmitate-induced insulin-resistant HSMM, GLP-1 activates SIRT1 through the PKA/cAMP pathway, which in turn enhances glucose uptake through GLUT4 and the insulin signaling pathway.

• 생명과학회지
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• 제23권1호
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• pp.131-136
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• 2013

Sirtuin family 단백질은 암, 당뇨, 심혈관 질환, 뇌신경계 질환과 같은 노화와 연관된 질병들의 발병에 중요한 역할을 하는 것으로 알려져 있다. 우선적으로 혈관내피세포를 이용하여 Hypoxia에서의 sirtuin family의 발현을 확인한 결과, SIRT2 mRNA가 가장 강하게 발현되는 결과를 얻었다. 혈관신생과정에서의 SIRT2 단백질의 생리학적 역할을 규명하고자, 본 실험실에서는 저산소상태에서의 SIRT2의 생리학적인 의미에 주안점을 두었다. Normoxia에서 SIRT2는 세포질에 존재하고 있으나, hypoxia에 의해서 SIRT2 단백질이 핵 내로 이동이 일어남을 확인하였다. 또한 hypoxia에 의해서 SIRT2와 혈관신생인자인 VEGF의 발현이 증가하며, Normoxia와 hypoxia 두 환경에서 혈관내피세포의 혈관형성능력이 SIRT2 inhibitor인 AK-1에 의해서 억제된 것을 확인하였다. 본 연구결과를 통해서 SIRT2가 혈관신생과정을 조절하는 중요한 역할을 함을 시사하였다.

• 한국축산식품학회지
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• 제40권1호
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• pp.106-117
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• 2020

Cellular senescence is associated with age-related vascular disorders and has been implicated in vascular dysfunctions. Here, we show that duck oil-loaded nanoemulsion (DO-NE) attenuates premature senescence of vascular smooth muscle cells (VSMCs) triggered by angiotensin II (Ang II). Compared with control nanoemulsion (NE), DO-NE significantly inhibited the activity of senescence-associated β-galactosidase, which is a biomarker of cellular senescence, in Ang II-treated VSMCs. SIRT1 protein expression was dose- and time-dependently induced in VSMCs exposed to DO-NE, but not in those exposed to NE, and SIRT1 promoter activity was also elevated. Consistently, DO-NE also dose-dependently rescued Ang II-induced repression of SIRT1 expression, indicating that SIRT1 is linked to the anti-senescence action of DO-NE in VSMCs treated with Ang II. Furthermore, the SIRT1 agonist resveratrol potentiated the effects of DO-NE on VSMCs exposed to Ang II, whereas the SIRT1 inhibitor sirtinol elicited the opposite effect. These findings indicate that DO-NE inhibits senescence by upregulating SIRT1 and thereby impedes vascular aging triggered by Ang II.

• Biomolecules & Therapeutics
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• 제31권1호
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• pp.73-81
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• 2023

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

• Molecules and Cells
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• 제43권7호
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• pp.632-644
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• 2020

The molecular mechanism underlying autophagy impairment in the retinal pigment epithelium (RPE) in dry age-related macular degeneration (AMD) is not yet clear. Based on the causative role of poly(ADP-ribose) polymerase 1 (PARP1) in RPE necrosis, this study examined whether PARP1 is involved in the autophagy impairment observed during dry AMD pathogenesis. We found that autophagy was downregulated following H₂O₂-induced PARP1 activation in ARPE-19 cells and olaparib, PARP1 inhibitor, preserved the autophagy process upon H₂O₂ exposure in ARPE-19 cells. These findings imply that PARP1 participates in the autophagy impairment upon oxidative stress in ARPE-19 cells. Furthermore, PARP1 inhibited autolysosome formation but did not affect autophagosome formation in H₂O₂-exposed ARPE-19 cells, demonstrating that PARP1 is responsible for impairment of late-stage autophagy in particular. Because PARP1 consumes NAD⁺ while exerting its catalytic activity, we investigated whether PARP1 impedes autophagy mediated by sirtuin1 (SIRT1), which uses NAD⁺ as its cofactor. A NAD⁺ precursor restored autophagy and protected mitochondria in ARPE-19 cells by preserving SIRT1 activity upon H₂O₂. Moreover, olaparib failed to restore autophagy in SIRT1-depleted ARPE-19 cells, indicating that PARP1 inhibits autophagy through SIRT1 inhibition. Next, we further examined whether PARP1-induced autophagy impairment occurs in the retinas of dry AMD model mice. Histological analyses revealed that olaparib treatment protected mouse retinas against sodium iodate (SI) insult, but not in retinas cotreated with SI and wortmannin, an autophagy inhibitor. Collectively, our data demonstrate that PARP1-dependent inhibition of SIRT1 activity impedes autophagic survival of RPE cells, leading to retinal degeneration during dry AMD pathogenesis.

• 생명과학회지
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• 제22권10호
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• pp.1277-1285
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• 2012

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)은 암세포 선택적으로 작용하므로서 유용한 항암제로 주목 받고 있다. 그러나, TRAIL 에 내성을 나타내는 암세포도 많이 존재한다. 그러므로 TRAIL 내성을 극복할 수 있는 방법을 고안하는 연구는 암 치료 요법에 매우 중요하다. 본 연구에서는 SIRT1 siRNA 또는 SIRT1 inhibitor인 amurensin G를 사람 유방암세포에 처리하면 DR5및 c-Myc의 발현 증강과 c-$FLIP_{L/S}$ 및 Mcl-1 발현 억제를 유도하므로서, TRAIL 에 내성을 나타내는 사람유방암세포 MCF-7 세포의 TRAIL 감수성을 증강시킴을 알 수 있었다. 또한, SIRT1 억제에 의한 caspase 활성화, PARP cleavage 및 Bcl-2 발현감소를 나타내었다. 이러한 연구결과는 SIRT1 저해에 의한 DR5 유도와 함께 c-FLIP 발현 억제가 TRAIL 내성 암세포의 TRAIL 반응성 증강에 유용한 기전으로 사용 될 수 있음을 시사하였다.

• Biomolecules & Therapeutics
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• 제19권3호
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• pp.282-287
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• 2011

Sirt1, a nicotinamide adenine dinucleotide ($NAD^+$)-dependent histone deacetylase, is known to deacetylate a number of proteins that are involved in various cellular pathways such as the stress response, apoptosis and cell growth. Modulation of the stress response by Sirtuin 1 (Sirt1) is achieved by the deacetylation of key proteins in a cellular pathway, and leads to a delay in the onset of cancer or aging. In particular, Sirt1 is known to play an important role in maintaining genomic stability, which may be strongly associated with a protective effect during tumorigenesis and during the onset of aging. In these studies, Sirt1 was generated in stably expressing cells and during the stimulation of DNA damage to examine whether it promotes survival. Sirt1 expressing cells facilitated the repair of DNA damage induced by either ionizing radiation (IR) or bleomycin (BLM) treatment. Fastened damaged DNA repair in Sirt1 expressing cells corresponded to prompt activation of Chk2 and ${\gamma}$-H2AX foci formation and promoted survival. Inhibition of Sirt1 enzymatic activity by a chemical inhibitor, nicotinamide (NIC), delayed DNA damage repair, indicating that promoted DNA damage repair by Sirt1 functions to induce survival when DNA damage occurs.

• Korean Circulation Journal
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• 제54권4호
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• pp.172-186
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• 2024

Background and Objectives: Long-term pathological myocardial hypertrophy (MH) seriously affects the normal function of the heart. Dronedarone was reported to attenuate left ventricular hypertrophy of mice. However, the molecular regulatory mechanism of dronedarone in MH is unclear. Methods: Angiotensin II (Ang II) was used to induce cell hypertrophy of H9C2 cells. Transverse aortic constriction (TAC) surgery was performed to establish a rat model of MH. Cell size was evaluated using crystal violet staining and rhodamine phalloidin staining. Reverse transcription quantitative polymerase chain reaction and western blot were performed to detect the mRNA and protein expressions of genes. JASPAR and luciferase activity were conducted to predict and validate interaction between forkhead box O3 (FOXO3) and protein kinase inhibitor alpha (PKIA) promoter. Results: Ang II treatment induced cell hypertrophy and inhibited sirtuin 1 (SIRT1) expression, which were reversed by dronedarone. SIRT1 overexpression or PKIA overexpression enhanced dronedarone-mediated suppression of cell hypertrophy in Ang II-induced H9C2 cells. Mechanistically, SIRT1 elevated FOXO3 expression through SIRT1- mediated deacetylation of FOXO3 and FOXO3 upregulated PKIA expression through interacting with PKIA promoter. Moreover, SIRT1 silencing compromised dronedarone-mediated suppression of cell hypertrophy, while PKIA upregulation abolished the influences of SIRT1 silencing. More importantly, dronedarone improved TAC surgery-induced MH and impairment of cardiac function of rats via affecting SIRT1/FOXO3/PKIA axis. Conclusions: Dronedarone alleviated MH through mediating SIRT1/FOXO3/PKIA axis, which provide more evidences for dronedarone against MH.

• Asian Pacific Journal of Cancer Prevention
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• 제15권22호
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• pp.10015-10020
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• 2014

Background: Fentanyl is used as an analgesic to treat pain in a variety of patients with cancer and recently it has become considered to also act as an antitumor agent. The study present was designed to investigate the effects of fentanyl on colorectal cancer cell growth and plausible mechanisms. Materials and Methods: The human colorectal carcinoma cell line HCT116 was subcutaneously injected into nude mice. The viability of HCT116 was tested by MTT assay, and apoptosis by flow cytometry and caspase-3 activity. The expression of Sirt1 and NF-${\kappa}B$ were evaluated by Western blotting and the levels of Sirt1 and NF-${\kappa}B$ by fluorescence method. SiRNA was used to silence and Ad-Sirt1 to overexpress Sirt1. Results: Our data showed that fentanyl could inhibit tumor growth, with increased expression of Sirt1 and down-regulation of Ac-p65 in tumors. Compared with control cells without treatment, HCT116 cells that were incubated with fentanyl had a higher apoptotic rate. Moreover, fentanyl could increase expression and activity of Sirt1 and inhibitor expression and activity of NF-${\kappa}B$, which might be mechanisms of fentanyl action. Conclusions: Fentanyl increased colorectal carcinoma cell apoptosis by inhibition of NF-${\kappa}B$ activation in a Sirt1-dependent manner.